• Membrane Journal
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• v.33 no.2
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• pp.77-86
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• 2023

In this study, pore-filled ion exchange membranes with low membrane resistance and high hydroxide ion conductivity was developed. To improve alkali durability, a porous substrate made of polytetrafluoroethylene was used, and a copolymer was prepared using monomers 2-(dimethyl amino) ethyl methacrylate (DMAEMA) and vinyl benzyl chloride (VBC) for pores. divinyl benzene (DVB) was used as the cross-linker, and ion exchange membranes were prepared for each cross-linking agent content to study the effect of the cross-linker content on DMAEMA-DVB and VBC-DMAEMA-DVB copolymers. As a result, chemical stability is improved by using a PTFE material substrate, and productivity can be increased by enabling fast photo polymerization at a low temperature by using a low-pressure UV lamp. To confirm the physical and chemical stability of the ion exchange membrane required for an anion exchange membrane fuel cell, tensile strength, and alkali resistance tests were conducted. As a result, as the cross-linking degree increased, the tensile strength increased by approximately 40 MPa, and finally, through the silver conductivity and alkali resistance tests, it was confirmed that the alkaline stability increased as the cross-linking agent increased.

• Membrane Journal
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• v.25 no.4
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• pp.310-319
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• 2015

Three kinds of anion-exchangeable functional groups with different hydrocarbon molecular structures were introduced to vinyl benzyl chloride-based membrane to understand the effect of attached function in anion-exchange membrane. Trimethylamine (TMA) as an aliphatic fuction, N-methylpiperidine (MP) as an alicyclic fuction and pyridine (Py) as an aromatic function were introduced by amination. The respective reactivity was observed by the trace of membrane resistance( MER)/ion exchange capacity (IEC) and the increasing order of reactivity was Py < MP < TMA. Meanwhile, SEM photograph showed the attached Py ion-exchange membrane was the most homogenous and compact structure in the study. In electrochemical properties, the attached Py ion-exchange membrane showed the MER ($5.0{\Omega}{\cdot}cm^2$ >, in 0.5 mol/L NaCl), comparable to those of commercial membrane (AMX). All results showed that the resonance structure of attached functional group might contribute to the preparation of homogenous anion-exchange membrane.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.11a
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• pp.39-42
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• 2004

• Proceedings of the Membrane Society of Korea Conference
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• 1996.10a
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• pp.71-72
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• 1996

Polyetherimide(PEI)계의 고분자는 막 성능이 우수하고 내열성과 내유기용매성 등이 우수한 열가소성수지로서 film, sheet, tubular형으로 만들 수 있어 한외여과막이나 역삼투막, 기체분리막 등에 이용되고 있다. 한편 투과속도를 높이고, fouling을 줄이기 위한 친수성 향상은 막 소재의 화학적 개질에 있어서 주된 목표이다. sulfonation은 막 재질의 소수성을 감소시켜 water permeability를 향상시키는데 있어서 매우 유용한 방법으로 이온교환수지, 이온교환막, anion형 하전막의 제조에 이용되어 왔다. 본 실험에서는 polyetherimide계 고분자를 chlorosulfonic acid(CSA)를 이용하여 술폰화시킨 sulfonated polyetherimide(SPEI)를 제조하여 막 성능을 측정하였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.59.1-59.1
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• 2009

레독스 흐름 배터리 (Redox Flow Battery)는 외부의 탱크 등에 저장해 둔 활성물질(이온 가수가 변화는 금속) 의 용액을 펌프로 전해셀에 공급하여 충전 방전하는 배터리로 신재생 에너지인 풍력과 태양광 발전, 야간의 잉여 전력 저장 등 대용량 전력 저장 장치로 관심이 높아지고 있다. 대표적인 레독스 흐름 배터리로 알려진 바나듐 레독스 흐름 배터리는 이온 교환막 사용으로 인하여 전기전도도, 기계적 강도, 투과도 및 전해질 내의 화학적 안정성 등 여러 가지 문제점과 함께 비용 문제점을 야기한다. 하지만 새로운 용해 납 레독스 흐름 배터리는 이온 교환막을 사용하지 않아 바나듐 레독스 흐름 배터리의 문제점 및 시설비가 절약되는 장점이 있어 새로이 연구되지고 있다. 본 연구는 레독스 흐름 배터리에 주로 이용되는 카본 전극재료의 따라 형성되는 Pb, $PbO_2$ 박막의 미세 구조를 및 에너지 효율 특성을 분석하였다. 실험은 half-cell로 이루어졌으며 작업전극은 Carbon felt, Ordered Graphite, Disordered Graphite, Glassy Carbon 등을 여러 카본 재료를 사용하였고, 상대전극은 Pt, 기준전극으로 Ag/AgCl를 사용하여 Cyclic Voltammetry특성과 충방전 특성을 연구하였다. 전해질은 Lead Carbonate ($PbCO_3$)+Methanesulfonic acid ($CH_3SO_3H$) 들어간 수용성 전해질을 교반을 통해 이용하였다. 여러 carbon 전극재료와 생성된 Pb, $PbO_2$ 막의 표면구조, 미세구조, 상들의 변화는 XRD, SEM, EDX, Raman등을 통하여 분석하였으며, 전기화학 공정의 변수와 전극에 따른 에너지 효율특성에 대하여 고찰해 보았다.

• Journal of the Korean Electrochemical Society
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• v.3 no.1
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• pp.57-62
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• 2000

Sulfonated Polysulfone (SPSF) cation-exchange membranes were synthesized by introducing various ratio of chlorosulfuric acid (CSA) onto the main chain of polysulfone (PSF). Properties such as ion exchange capacity, water content, liked ion concentration, and partition coefficient were measured, respectively. Through the analysis of DSC and TGA, it has been shown that glass transition temperature increased and weight loss decreased as sulfuric acid group concentration increased. Structure of membrane measured by AFM and SEM was seen to be asymmetric. Apparent diffusion coefficient of sodium ions through SPSF membrane by AC impedance was increased as sulfuric acid group concentration increased.

• Applied Chemistry for Engineering
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• v.8 no.1
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• pp.67-75
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• 1997

Heterogeneous cation exchange membrane consisting of cation exchange resin particles (diameter of less than $149{\mu}$) which are finely dispersed in a polyethylene matrix, were produced as forms of sheet. The characteristics were measured after treating hot water or saturated sodium chloride. When membranes were treated with hot water or saturated sodium chloride, cation exchange resin particles swell and expand pushing away the polyethylene matrix of membranes. The above treatment results the formation of narrow cavities between a cation exchange resin particles and polyethylene matrix, and the formation of fine micro-cracks on the polyethylene matrix. Thus, we were obtained good physical and electrochemical properties. On the treatment with hot water or saturated sodium chloride, the optimum conditions for good heterogeneous cation exchange membrane were treatment time of 30min and treatment temperature of $90^{\circ}C$.

• Membrane Journal
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• v.12 no.3
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• pp.171-181
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• 2002

The parameter which determines the plateau length of current-voltage curve for ion- exchange membranes was studied at various concentrations of NaCl and different flow rates. Moreover, the feasibility of the electrodialytic removal of 0.1 M NaCl solution at various current densities was tested by assessing the electrodialysis performance parameters such as salt removal efficiency, current efficiency, energy consumption and water dissociation. The diffusion boundary layer (DBL) thickness decreased with the NaCl concentration and flow rate of fled solution and it was observed that the plateau length of current-voltage curves was related with the DBL thickness. The removal efficiency and current efficiency were not affected significantly by the current densities even at the overlimiting current region indicating that most current were passed by electrolyte, and water dissociations are not responsible for the overlimiting current. Energy consumption increased when the current density supplied exceeded the limiting current density (LCD) values, because additional energy was necessary to overcome the plateau potential. Beyond the LCD values the energy consumption required to get a certain removal efficiency was not affected by the current density applied. The result suggests that it is allowed to operate electrodialysis processes at as high as possible current density unless water-splitting does not occur.

• Membrane Journal
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• v.17 no.1
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• pp.54-60
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• 2007

In this research, the cation-exchange membrane (SS membrane) containing sulfonic acid group was prepared by radiation induced grafted polymerization onto a porous hollow fiber membrane to effectively remove ammonia which was produced by urea decomposition for peritoneum dialysis system. And the metal ionic cross-linking cation-exchange membrane (SS-M membrane) was prepared by the adsorption of metallic ions (Cu, Ni, Zn) to the SS membranes. The pure water flux and adsorption capacities of ammonia to SS and SS-M membranes were examined. The pure water flux of SS membrane decreased rapidly with the density of $SO_3H$ group increasing. As the metallic ions were adsorbed to the SS membrane, the pure water flux was increased. The adsorption capacities of ammonia at the SS membrane increased with increasing of density of $SO_3H$ group. The ion-exchange capacity of ammonia of the SS membrane was approximately proportional 1 : 1 to the density of $SO_3H$ group. The SS membrane had higher adsorption capacities than the SS-M membrane. The highest adsorption capacities of SS and SS-M membrane appeared the highest pH 9.

• Membrane Journal
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• v.14 no.2
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• pp.108-116
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• 2004

In this study, the pore-filled ion-exchange membranes were prepared by using the asymmetric PVDF membrane as a nascent membrane. First, the solution of PVBCI having the chlorornethylate aryl ring of 80 percents and DABCO was made with the mixed solvent of THF and DU (8:2). These mixed solution was then, filled in the pores of PVDF membrane, and left for a day to complete the gelation. Finally the pore-filled anion-exchange membrane is obtained fallowed by the amination of the remaining chloromethyl groups with trimethylamine (TMA, 40 wt% in water) forming the positive ammonium ion sites. This 2 step procedure enabled us to produce the pore-filled membranes without change of size, and to control the properties of final membrane with various degree of cross-linking. The results of SEM and AFM showed the polyelectrolyte existed in the pores of nascent membrane as a certain configuration. From the investigation of the solvent affecting much to the permeability and rejection, it was found that the membranes using mixed solvent of THE and DMF (8:2) showed better performances than the membranes produced by THF only. The result of an investigation for the water permeability of the final membrane at low pressure (100 Kpa) showed a typical ultrafiltration membrane's permeability (8 ∼ 10 kg/$m^2$hr) and good values of rejection (55∼60 percent).